Design, synthesis, and biological evaluation of 1,6-naphthyridine-2-one derivatives as novel FGFR4 inhibitors for the treatment of colorectal cancer

Aberrant FGFR4 signaling has been implicated in the development of several cancers, making FGFR4 a promising target for cancer therapy. Several FGFR4-selective inhibitors have been developed, yet none of them have been approved. Herein, we report a novel series of 1,6-naphthyridine-2-one derivatives as potent and selective inhibitors targeting FGFR4 kinase. Preliminary structure-activity relationship analysis was conducted. The screening cascades revealed that 19g was the preferred compound among the prepared series. 19g demonstrated excellent kinase selectivity and substantial cytotoxic effect against all tested colorectal cancer cell lines. 19g induced significant tumor inhibition in a HCT116 xenograft mouse model without any apparent toxicity. Notably, 19g exhibited excellent potency in disrupting the phosphorylation of FGFR4 and downstream signaling proteins mediated by FGF18 and FGF19. Compound 19g might be a potential antitumor drug candidate for the treatment of colorectal cancer.